Tympanoplasty - Lateral graft

Considerations

• • Basic concept and terminology

    • Lateral (AKA overlay, onlay) refers to the position of the graft relative to the ossicles

    • The lateral graft is combined with the postauricular approach

• Indication

  • Perforation involving most or all of the central tympanic membrane (eg, subtotal or total)

  • Generalized atelectasis of the pars tensa

  • Advantages over the medial graft for long-term success

    • Wider attachment of the lateral graft to all four portions of the canal wall

    • Negative middle-ear pressure, which is usually present in children who have middle-ear disease, is actually helpful to maintain graft position

  • Tympanoplasty classification - based on the most lateral intact structure that remains connected to the inner ear

    • Type I: Tympanoplasty (or myringoplasty) when all three ossicles are normal, which should result in normal hearing

    • Type II: Tympanoplastic graft (or tympanic membrane) is in contact with the incus and the stapes is present, both of which are connected and mobile, which ideally should result in a minimal hearing loss of only 2.5 dB

    • Type III: Tympanoplastic graft (or tympanic membrane) is in direct contact with the suprastructure of the stapes (columella effect), which should result in a hearing loss of only 2.5 dB; also known as myringostapediopexy

    • Type IV: Ossicular chain is absent and the tympanic membrane is in contact with a mobile stapes footplate, which theoretically should result in a 27.5 dB hearing loss; also known as a cavum minor

    • Type V: A window is surgically made in the horizontal semicircular canal, which should result in hearing similar to a Type IV; also known as a fenestration

• 2006: Lateral tympanoplasty for total or near-total perforation: prognostic factors

• 2015: Success of lateral graft technique for closure of tympanic membrane perforations

Preparation

• • Balance and prepare the assistant viewfinder on the operative microscope 

    • Place assistant viewfinder opposite the side of the operated ear

  • Shave a small area of hair posterior and superior to the planned postauricular incision

  • Local anesthesia (1% Lidocaine with 1:100,000 Epinephrine - or - only 1:100,000 Epinephrine when monitoring the facial nerve)

    • Infiltrate into all four quadrants of the ear canal (6, 9, 12, and 3 o’clock) just lateral to the bony-cartilaginous junction and the graft site, for hemostasis and to enhance the anesthesia, using the Lampert speculum

    • Infiltrate the postauricular sulcus 

  • Facial nerve monitor 

Procedure

• • An incision for a “long” Koerner flap is made closer (approximately 2 mm) to the posterior annulus than the usual incision

  • The postauricular incision and approach are completed

    • An incision is made a few millimeters posterior to the postauricular crease

      • In children younger than 4 years of age, the incision is made away from the stylomastoid foramen and the facial nerve

    • The postauricular soft tissue is exposed, place two Weitlaner retractors opposite one another

    • A “T” incision is made in postauricular soft tissue though the periosteum and is elevated with a periosteal elevator toward the EAC

    • Connect to the transcanal incisions to form a Koerner flap

    • A Penrose drain is used to retract the Koerner flap anteriorly, which is fastened to the surgical drape in front of the ear

      • The Penrose drain also protects the Koerner flap when a self-retaining retractor is inserted 

• The fascia graft is taken from the temporalis muscle 

• An anterior incision for the anterior flap is made approximately 2 mm lateral to the anterior annulus and is connected to the Koerner flap incision

  • If the ear canal is too narrow to visualize the anterior canal wall and annulus, a canaloplasty (primarily in the lateral portion of the posterior canal wall), using an air drill, is helpful; the canaloplasty is readily performed, since the two pedical flaps are retracted out of the field and the bony canal is completely exposed

  • The anterior flap is elevated, rolled, and tucked laterally out of the medial portion of the canal

  • A medial strip of canal skin is adjacent to the annulus, and the entire outer epithelial layer of the tympanic membrane is elevated and discarded 

  • The canal wall is curetted to remove any remnants of canal skin; a microdrill is another option

    • When indicated, a canaloplasty can be performed at this stage

  • The annulus is elevated to examine the mesotympanum and the ossicles

  • The middle ear is filled with Gelfoam

  • A fascia graft is placed over the tympanic membrane remnant, overlapping onto the medial canal wall

    • Four pieces of Surgicel are placed over the edge of the graft and onto the canal wall to “fix” the graft

  • The anterior pedicle flap is replaced and overlaps the lateral edge of the anterior portion of the fascia graft

  • The Penrose drain is removed, and the Koerner flap, which overlaps the lateral edge of the posterior portion of the fascia graft, is replaced

  • A layer of Gelfoam is placed over the tympanic membrane remnant and graft, and two strips of Adaptic gauze impregnated with antibiotic ointment are inserted into the external canal

• The postauricular incision is approximated with suture and dressed with steri-strips

• A Glasscock pressure dressing is applied

Sample operative report

Findings:

*** subtotal perforation, concern for skin ***

Performed *** lateral graft tympanoplasty 

Canoloplasty for a narrowed EAC

Procedure details:

Patient was brought to the OR. Placed in the supine position. He was placed under general endotracheal anesthesia. The table was then turned 180 degrees. The facial nerve monitor was placed and tested. L ear canal and postauricular crease were injected with 1% lidocaine with epinephrine. He was noted to have both anterior and posterior TM perforation, subtotal in nature, curled edges with skin potentially on the undersurface of the TM and on the anterior malleus.

The patient was then prepped and draped in the normal sterile fashion. 12 o'clock and 6 o'clock lateral canal incisions were made as well as a connecting incision in the posterior canal. The postauricular incision was made and taken down the level of the temporalis. Temporalis fascia was harvested, and the lateral EAC skin was elevated. The flap was then retracted anteriorly with a penrose. An anterior EAC incision was made and the medial skin was then elevated, and moving across the annulus and onto the fibrous TM. The skin was removed and saved in saline. The EAC was widened using cutting and diamond burrs to gain exposure. The posterior fibrous TM was elevated and the ossicles were checked and mobile; Incudopexy was noted and easily separated from the TM. All visible skin was removed along with the involved TM. Skin was removed from the malleus; The malleus was preserved. Fascia graft was placed over the remaining anulus, a notch was made in the graft to wrap around the umbo. Skin fract was cut into triangles and placed over the edges of the fascia graft and medial bony EAC. The medial EAC was packed with gelfoam soaked in Floxin. The penrose was the removed and the lateral flap was replaced, and the lateral EAC was packed with gelfoam and two long otowicks. 

The postauricular incision was closed in 3 layers with 3-0 polysorb, 4-0 biosyn and 5-0 fast gut. Steristrips were applied. A cotton ball was placed in the meatus and a Glasscock dressing was applied. The patient was awoken from anethesia without complications.

Post-op

• POD 2 

  • • Remove Glasscock dressing

    • Start Floxin drops 

• POD 7

• • Remove EAC pack

  • Gently suction lateral EAC Gelfoam

  • Remove post-auricular seri-strips 

• POD 14

• • Gently suction medial EAC Gelfoam

• POD 28

• • RTC for repeat evaluation

  • Complications and challenges

    • “Blunting” in the anterior sulcus and lateralization of the graft may be observed

      • When lateralization of the graft is occurs, it usually can be attributed to external otitis, otitis media, or both, that occur in the postoperative period

    • Iatrogenic implantation cholesteatoma, between the graft and the remnant of the tympanic membrane or in the canal wall, is not an uncommon

    • Compared to a medial graft, a lateral graft may require up to several months longer for the tympanic membrane to assume a “normal” appearance

Pearls & Pitfalls

High-Yield

Links

• eMedicine - Tympanoplasty

• OPEN ACCESS ATLAS OF OTOLARYNGOLOGY, HEAD & NECK OPERATIVE SURGERY - MYRINGOPLASTY & TYMPANOPLASTY

• UTMB - Tympanoplasty

• YouTube (2:48) - Lateral graft tympanoplasty (right ear)

• YouTube (3:44) - Endoscopic lateral cartilage perichondrial graft tympanoplasty

• YouTube (4:03) - Endoscopic Lateral Tympanoplasty (left ear)